Aluminum bromide in relatively pure state is useful as a catalyst in, for example, polymerization and alkylation processes. The compound, unfortunately, possesses certain characteristics which make its preparation and storage in large quantities unfeasible from a commercial and safety standpoint. It is readily decomposed by moisture, liberating fumes of hydrogen bromide. It reacts with water with explosive violence, evolving a great amount of heat. Storage of aluminum bromide is normally in sealed containers under dry inert gas, but there are nevertheless certain disadvantages arising from storage even under the best of conditions. First, there is difficulty in handling the compound because it usually forms lumps and must be ground down to a powder in a dry box prior to dissolving it for use. Secondly, if the entire container of aluminum bromide is not used at one time, successive uses will involve material of lower activity (i.e. less pure AlBr.sub.3) owing to its reaction with traces of moisture upon handling. Thirdly, persons who must handle aluminum bromide may be exposed to a potential health hazard. Since, in general, only relatively small amounts of aluminum bromide are needed at any one time, preparation of large amounts of the compound is not commercially convenient. Thus, the economic advantages flowing from techniques for producing large amounts of chemical products have not been available for aluminum bromide of high purity.
The generally used commercial method for preparing aluminum bromide involves treating aluminum with bromine and then distilling the product. This process requires extensive and elaborate equipment and is quite expensive to operate, particularly when only small amounts of the product are desired.
It is, therefore, a principal object of this invention to develop a method for preparing aluminum bromide which is economically attractive when the compound is to be prepared in small quantities. It is another object to develop a method for preparing aluminum bromide in somewhat larger quantities which can be stored in a readily available state without loss of activity resulting from successive uses.
It is a further object of this invention to provide a rapid process for preparing aluminum bromide from starting materials which are readily available. Other objects and advantages will become apparent from the following description of the invention.